The remaining candidates each have support below 5%. Mike Huckabee, in particular, has seen a sharp drop off in Iowa – a state he won with relative ease in the 2008 race – where his support is down to just 2%.

As for the increasingly evident GOP top tier, note that the combined support for Cruz and Rubio does not quite reach Trump’s standing, at least not in this survey.

On the issues, the same poll found Iowa Republicans trust Trump to an almost ridiculous degree on the economy and illegal immigration. Carson leads among GOP Iowans on social issues and the candidate whose values best represent voters’ values.

A third of Iowans see Trump as the most electable Republican in the field.

Public Policy Polling, meanwhile, published these similar results out of Iowa a couple of days ago.

1. Donald Trump: 22% (down two points from September)

2. Ben Carson: 21% (up four points)

3. Ted Cruz: 14% (up six points)

4. Marco Rubio: 10% (up two points)

Note, both of these surveys were conducted entirely after last week’s debate, which means it includes all of the post-event media hype surrounding Rubio’s performance.

In many circles, it’s still assumed support for the Amateur Duo will soon fade, leaving room for Rubio and Cruz to move up, but who’s best positioned to benefit from a Trump/Carson drop – if there’s ever a Trump/Carson drop – remains to be seen.